At this point, Western medicine is mostly focused on blood-letting, vomiting/purging, and a range of chemical interventions, such as calomel, which uses mercury to purge the body–resulting in a range of other toxic harms. "Irregular" medicines are treatments that attempt to provide care through other means, particularly those that don't cause harm on the way to providing a cure. Additionally, the unceasing waves of yellow fever epidemics lead many to look for "alternative" forms of treatment. Many of these different forms that begin to emerge are regional and are centered around specific teachers in specific areas.